Depends on if being good makes me feel good. In some games, healing strangers on the street makes you feel like you're actually doing good deeds (inFAMOUS), but in others, it feels like you're just XP-grinding (Okami). I wish you could be evil in Okami. I would continually spawn the sun so that the people would never get any sleep and become aggravated.
Also, if there are other people around, I become cartoonishly evil for laughs. I once played Morrowind with a friend, and here's how events unfurled: A creepy elf thing was telling me stuff I couldn't understand because I wasn't wearing my headphones, and then I was supposed to go to the duke or something. On the way, I proceeded to stab every guard I met, and steal everything I could find. I even tried to steal some chairs, though the game wouldn't let me. I was able to steal a few cups and a candlestick. Then when I got to the duke's room he had a sword and killed me to death for some reason. Was it something I said? Or stole? Or stabbed?
Also, if there are other people around, I become cartoonishly evil for laughs. I once played Morrowind with a friend, and here's how events unfurled: A creepy elf thing was telling me stuff I couldn't understand because I wasn't wearing my headphones, and then I was supposed to go to the duke or something. On the way, I proceeded to stab every guard I met, and steal everything I could find. I even tried to steal some chairs, though the game wouldn't let me. I was able to steal a few cups and a candlestick. Then when I got to the duke's room he had a sword and killed me to death for some reason. Was it something I said? Or stole? Or stabbed?